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The Effects of Kynurenine Aminotransferase Inhibition in People With Schizophrenia

NCT04013555 · Status: COMPLETED · Phase: PHASE1/PHASE2 · Type: INTERVENTIONAL · Enrollment: 88

Last updated 2026-02-11

Study results available
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Summary

Kynurenic acid (KYNA) is a naturally occurring chemical in the brain. Studies with rodents indicate that levels of KYNA can impact levels of the neurotransmitters glutamate and dopamine. One way to reliably increase KYNA levels is by ingesting the amino acid tryptophan. Tryptophan is a normal part of the human diet. Tryptophan gets metabolized/changed to other chemicals in the body- including KYNA. By giving people 6 grams of tryptophan, the investigators will be able to increase the KYNA level in a controlled way. The investigators will then be able to study the effects of KYNA on neurotransmitters by using cognitive tests and magnetic resonance imaging techniques (measuring brain activity and brain chemistry using the MRI magnet).

The overall goal of the study is to examine how the medication N-acetylcysteine (NAC), when added to tryptophan, affects various cognitive functions, such as verbal and visual memory. The investigators will also use magnetic resonance imaging (MRI) to examine how NAC affects brain activity and chemicals.

Conditions

  • Schizophrenia
  • Schizoaffective Disorder
  • Schizophreniform Disorder

Interventions

DRUG

N-acetylcysteine (NAC)

Flavored effervescent formulation

DRUG

Placebo

Flavored effervescent formulation designed to mimic NAC

DRUG

Tryptophan

Oral slurry form

Sponsors & Collaborators

  • University of Maryland, Baltimore

    lead OTHER

Principal Investigators

  • Robert W Buchanan, M.D. · University of Maryland

Study Design

Allocation
RANDOMIZED
Purpose
OTHER
Masking
QUADRUPLE
Model
CROSSOVER

Eligibility

Min Age
18 Years
Max Age
55 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2020-01-20
Primary Completion
2024-08-14
Completion
2024-08-14
FDA Drug
Yes

Countries

  • United States

Study Locations

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Entities

Drugs
Diseases

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT04013555 on ClinicalTrials.gov